Bug#989550: suitesparse: enhance 64-bit support in suitesparse

[Drew Parsons]

Package: suitesparse
Severity: normal
Control: block -1 by 961183
Control: block 961977 by -1

We've been introducing a 64 bit-build for the computational stack.
This refers mainly to 64-bit indexing, enabling computation of
extremely large systems (billions of degrees of freedom)

Some packages are already 64-bit enabled, including BLAS, PETSc.

SuiteSparse handles the 64-bit question by defining SuiteSparse_long
(and using idx_t with metis). If I understand the SuiteSparse
configuration correctly, this means a specific configuration option
doesn't need to be set for SuiteSparse to compute large systems.

But as part of the 64-bit computation stack in Debian, we'd need to
provide a separate suitesparse64 build in order to link suitesparse
against blas64 or metis64. (I'm assuming this is a thing we would want
to do in the context of 64-bit computation).

This affects cholmod, for instance, in the sense that cholmod uses
idx_t defined in metis.h.  IDXTYPEWIDTH is the quantity in metis.h
which we'll need to set to 64, in order to provide 64-bit Metis (this
is requested in Bug#961183).

Once metis64 is available, we'll be free to provide suitesparse64
i.e. libsuitesparse64-dev (it might be that header files can be
transferred to a libsuitesparse-common-dev to share with
libsuitesparse-dev),
libcholmod64-3 (or similar), etc.

Once suitesparse64 is available, we'll be able link it from petsc64,
which is currently linking to the standard build of suitesparse.

Drew


-- System Information:
Debian Release: 11.0
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